A rotor-type gas solenoid valve uses a rotor-type electromagnet as a drive element, in which a rotor core is fixed by means of a rotation shaft of the rotor-type electromagnet. A clearance between the rotor core and a stator core may be very small, while the rotation shaft and a bearing can produce a friction force. Since the diameter of the rotation shaft is much less than that of the rotor, this friction force is much less than the friction force directly generated by a direct contact between a spool and a solenoid wall in a solenoid-type electromagnet. The rotor-type electromagnet has a great initial attraction force, which just meets the requirement for overcoming the back pressure and the adhesive force between a valve port and a rubber sealing when the gas solenoid valve is opened. Moreover, a characteristic graph of the electric current versus the travel of the rotor-type electromagnet has a good linearity. Specifically, when the clearance between the rotor and the stator decreases, the initial attraction force will be relatively large, and the rotation torque will be considerably reduced as a rotation angle of the rotor increases; on the other hand, if the clearance between the rotor and the stator increases, the initial attraction force will be relatively small, and the rotation torque will be slightly reduced as a rotation angle of the rotor increases. Accordingly, the current-torque performance of the rotor-type electromagnet is in connection with the clearance between the rotor and the stator.
Like other kinds of electromagnets, the rotor-type electromagnet has the following properties: in the case that the ampere-turns of coil and the material of magnetic conductor are identical, the electromagnetic driving force is in inverse proportion to a length of magnetic circuit, but is in direct proportion to a cross-section area of the magnetic circuit; that is to say, the same effect can be achieved by reducing the cross-section area of the magnetic circuit correspondingly at the time of shortening the magnetic circuit. Meanwhile, the geometrical cross-section shape of a coil winding also directly influences the usage amount of lacquered wire and the resistance value of the coil winding in the case of the same turns of coil. For example, in the case of the same cross-section areas, a coil winding with a circular cross-section shape will lead to a much less usage amount of copper than a coil winding with a rectangular cross-section shape.
There are various rotor-type gas solenoid valves used in gas utensils. The current rotor-type gas solenoid valves have respective advantages and disadvantages, so that their structures are still have the necessity of being improved in order to meet the requirements of having a sound structure and an excellent performance, simplifying the manufacturing processes, saving material and reducing the cost.
Chinese Utility Model Patent published as No. CN2343444 discloses “a rotor-type closable gas regulating valve”, in which a rotor-type electromagnet without a stop iron is used as a drive element to directly drive a valve sheet clutch (valve plate clutch), which synchronously rotates with the rotation shaft and clings to the outlet valve port, so as to achieve the object of gas sealing and regulating. The rotor-type electromagnet adopts a horizontal structure, in which the planes of the rotor core and stator core are parallel. In the rotation range of the rotor, it is necessary to maintain a certain space. Thus, the magnetic circuit of the rotor-type electromagnet will be lengthened, because a rotor rotation space is reserved for the rotor at the coil winding side thereof. If the stator core of the rotor-type electromagnet is manufactured as one piece, the cost of manufacturing will be quite high. Accordingly, such a stator core is formed of thin-sheet magnetic conductive material (magnetic permeability material, such as silicon steel sheet) by punching-shearing and laminating processes. However, the core formed by laminating punched sheets has a rectangular cross-section shape in the portion of the stator coil winding. Correspondingly, in order to prevent the corners in the shape of rectangle from damaging insulating layers of the lacquered wire, the coil is necessarily provided with an insulating framework, so that the usage amount of copper for the coil with a rectangular cross-section is much more than that for the coil with a circular cross-section. In the rotor-type electromagnet of this patent, the concentricity between the rotor cambered surface and the stator cambered surface can be ensured by positioning of a bracket riveted on the stator, and the rotor and stator are easy to impact with each other due to insufficient concentricity when the clearance therebetween is small. A starting point of this regulating valve is located in a joint where the rotor cambered surface meets the stator cambered surface, and the rotor presses the valve sheet closely against the valve port by means of a regulating spring. In the case that the electric current of the coil winding is constant, the regulating spring can regulate the initial action force of a valve body via a regulating screw, but cannot regulate a skew degree of a characteristic graph of the rotor versus the drive current, and thus can not change a graph of the regulated gas flow of the valve body versus the current of coil winding on occasion; whereas this characteristic graph is often influenced by the materials of the rotor and the stator as well as the clearance and concentricity between the rotor and the stator. If the skew degree of the characteristic graph cannot be changed, the gas regulating valve will be unable to adapt to different regulating properties required by various gas utensils, and thus versatility and interchangeability of products can not be guaranteed. Although the regulating valve disclosed in this patent is used to regulate by a solution with a small clearance and a small swing angle of the rotor, the valve is a clap-fit structure, so that even a quite small displacement distance of the valve sheet would cause a considerable variation of gas flow, the advantage of long attraction travel of the rotor-type electromagnet can not be fully utilized. As a result, the regulation of the gas flow will be difficult to be performed and have a low regulation accuracy.
The Utility Model Patent published as No. CN2504449 with a title of “Rotor-Type Electromagnetic Regulating Valve” discloses a rotor-type electromagnet regulating valve consisted of a rotor-type electromagnet drive mechanism and a butterfly valve regulating mechanism, which are coaxially and directly connected with each other. As the electromagnet regulating valve employs a butterfly valve, the maximum rotation angle thereof is up to 80°, and thereby a relatively large clearance should be provided between the rotor and the stator of the rotor-type electromagnet thereof to meet such requirement, so that the propulsion power would be increased correspondingly. The rotor-type electromagnet of the embodiment illustrated in FIG. 13 of the drawings of this patent adopts a horizontal structure, so that there still exists some disadvantages, such as the magnetic circuit length being long, the usage amount of copper being large due to the coil winding with a rectangle shape, the concentricity between the rotor and the stator being difficult to be ensured, and so on. Since no screw can be available for regulation, and the gas flow has no initial position-limiting, the universality and interchangeability of regulating valve products are unable to be ensured due to the following factors, such as the magnetic conductive material of the rotor-type electromagnet, errors of the clearance and concentricity between the rotor and stator, variation of spring parameters, and so on. Therefore, this regulating valve is incapable of adapting to different requirements of various gas utensils. If a butterfly regulating mechanism is used to regulate the gas flow, the minimum gas flow can be merely ensured by machining precision of the butterfly sheet and through hole in the case that the starting point of the minimum gas flow is not adjustable. However, when the gas utensil uses liquefied petroleum gas and heat load is relatively small, even with machining precision error of 0.01 mm between the butterfly sheet and through hole, a considerable gas flow error would be caused. Therefore, machining precision should be improved in order to satisfy operating requirements. As the maximum rotation angle of the butterfly sheet is up to 80°, at this point, the driving force would be merely dozens of grams even though the power supplied to the rotor-type electromagnet is increased. Moreover, when the gas flow passing through the valve body is at its maximum level, the flow rate thereof may be beyond 10 m/s, the butterfly sheet will tremble under heavy impact of the gas flow and thus the regulation of the gas flow will be influenced correspondingly.
The Utility Model Patent published as No. CN2504449 also discloses a schematic view of a structure of a vertical rotor-type electromagnet in FIG. 15 of the drawings of specification thereof. As can be seen from FIG. 15, a reset spring of the electromagnet is located between a rotor and a coil winding, and a stator structure thereof is manufactured by means of a laminating method. Upon laminating, a laminated surface of the lamination needs to be transversely formed a cambered surface which is opposite to the rotor, so that it is very difficult in processing, and if the stator is manufactured as one piece, the processing cost will be quite high. Moreover, the fixation fitting between the rotor and the stator is not indicated in the figure. Obviously, in the illustrated vertical rotor-type electromagnet, the influence of the magnetic circuit on the effect of the electromagnetic action is neither taken into consideration, and nor do such factors as the regulation of the graph of the magnetic force and rotor travel versus the electric current, the way of precise positioning of con centricity between the rotor and the stator, the difficulty of processing and the high cost in a mass production of the stator structure, and so on.